This video shows how we can make an octahedron (3D) from a plain sheet of paper or metal which is 2D. The method uses Development of Solids which provides most optimized way of preparing the 2D surface for making the solid. This is important in engineering because it helps to reduce the wastage of the material and reduce the manufacturing cost by avoiding expensive operations such as cutting, welding etc. 3D shape is made by simply bending the sheet if proper development of solid is learnt for each 3D shape.